Since upgrading from InfluxDB plugin version 1.14 to 1.17 the jenkins_data measurement is now prefixing the project_name tag with an underscore.  From a quick look at the source code it appears that when the "replaceDashWithUnderscore" parameter is false (which is the default) then the code assumes you must have a custom prefix and prepends the project_name tag with customPrefix + "_".  If your Jenkins job doesn't have a custom prefix you end up with an underscore prefixed to the project name.  Looks like the code needs to be changed to something like:

 

String projectTagName;

if (this.replaceDashWithUnderscore)

{             projectTagName = renderedProjectName;        }

else if (customPrefix != null)

{             projectTagName = customPrefix + "_" + build.getParent().getName();        }

else

{         projectTagName = build.getParent().getName();        }